SM4国密

一、基础知识

SM4密码算法是一个分组算法，该算法的分组长度为128比特，密钥长度为128比特。

数据解密时，轮密钥的使用顺序相反，解密轮密钥是加密轮密钥的逆序。

 

二、加密过程

 

 

a、32次迭代得到X4~X35

x0~x3是明文输入

 

F函数中 rki是我们输入后经过变换的32个32位的轮密钥

 

1、F函数

 

2、T函数

 

把输入经过tao()变换，再经过L变换

首先是非线性变换tao

图中A是一个32位的字，图中是把A分成了四个8比特的字符串，然后通过查表生成一个新的字

Sbox表如下

 

其次是线性变换L:

 

 

b、反序变换

 

反序变换就是把X32,X33,X34,X35进行倒序

 

三、轮密钥的生成

 

我们的目的是得到32个32位的密钥

其中FK是系统参数CK为固定参数

1、T'函数

T’函数是与上面加密算法用到的T函数类似，不过改了一些东西 ，L线性变化是下面的变化:

2、系统参数FK与固定参数CK的取值

 

四、代码实现

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define SAR(x,n) (((x>>(32-n)))|(x<<n))    //循环移位//

#define L1(BB) BB^SAR(BB,2)^SAR(BB,10)^SAR(BB,18)^SAR(BB,24)

#define L2(BB) BB^SAR(BB,13)^SAR(BB,23)

/*系统参数*/
unsigned long FK[4] = {0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc};

/*固定参数*/
unsigned long CK[32] =
{
    0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
    0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
    0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
    0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
    0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
    0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
    0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
    0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
};

/*τ变换S盒*/
unsigned char TAO[16][16] =
{
    {0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05},
    {0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99},
    {0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62},
    {0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6},
    {0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8},
    {0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35},
    {0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87},
    {0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e},
    {0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1},
    {0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3},
    {0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f},
    {0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51},
    {0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8},
    {0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0},
    {0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84},
    {0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48}
};

unsigned long RK[32];

//tao变换 
int sm4_to_tao(unsigned char *in, unsigned char *out, int len)
{
    unsigned char a, b, c, d;
    int i = 0;

    for(i=0; i<len; i++)
    {
        a = in[i];
        b = a >> 4;
        c = a & 0x0f;
        d = TAO[b][c];
        out[i] = d;
    }

    return 0;
}

//两位或四位异或运算// 
int sm4_to_xor_2(unsigned char *a, unsigned char *b, unsigned char *out, int len)
{
    int i = 0;

    for(i=0; i<len; i++)
    {
        out[i] = a[i] ^ b[i];
    }

    return 0;
}

int sm4_to_xor_4(unsigned char *a, unsigned char *b, unsigned char *c, unsigned char *d, unsigned char *out, int len)
{
    int i = 0;

    for(i=0; i<len; i++)
    {
        out[i] = a[i] ^ b[i] ^ c[i] ^ d[i];
    }

    return 0;
}

//获取轮密钥// 
int sm4_get_rki(unsigned long *mk)
{
    unsigned long k[36];
    unsigned long u, v, w;
    int i = 0;
    int j = 0;

    sm4_to_xor_2((unsigned char *)mk, (unsigned char *)FK, (unsigned char *)k, 16);

    for(i=0; i<32; i++)
    {
        sm4_to_xor_4((unsigned char *)(k+i+1), (unsigned char *)(k+i+2), (unsigned char *)(k+i+3), (unsigned char *)(CK+i), (unsigned char *)(&u), 4);

        sm4_to_tao((unsigned char *)(&u), (unsigned char *)(&v), 4);

        w = L2(v);

        sm4_to_xor_2((unsigned char *)(k+i), (unsigned char *)(&w), (unsigned char *)(k+i+4), 4);

        RK[i]= k[i+4];
    }

    return 0;
}

int sm4_one_enc(unsigned long *mk, unsigned long *in, unsigned long *out)
{
    unsigned long x[36];
    unsigned long u, v, w;
    int i = 0;
    int j = 0;

    x[0] = in[0];
    x[1] = in[1];
    x[2] = in[2];
    x[3] = in[3];

    sm4_get_rki(mk);

    for(i=0; i<32; i++)
    {
        sm4_to_xor_4((unsigned char *)(x+i+1), (unsigned char *)(x+i+2), (unsigned char *)(x+i+3), (unsigned char *)(RK+i), (unsigned char *)(&u), 4);

        sm4_to_tao((unsigned char *)(&u), (unsigned char *)(&v), 4);

        w = L1(v);

        sm4_to_xor_2((unsigned char *)(x+i), (unsigned char *)(&w), (unsigned char *)(x+i+4), 4);

        x[i+4];
    }

    out[0] = x[35];
    out[1] = x[34];
    out[2] = x[33];
    out[3] = x[32];

    return 0;
}

int sm4_one_dec(unsigned long *mk, unsigned long *in, unsigned long *out)
{
    unsigned long x[36];
    unsigned long u, v, w;
    int i = 0;
    int j = 0;

    x[0] = in[0];
    x[1] = in[1];
    x[2] = in[2];
    x[3] = in[3];

    sm4_get_rki(mk);

    for(i=0; i<32; i++)
    {
        sm4_to_xor_4((unsigned char *)(x+i+1), (unsigned char *)(x+i+2), (unsigned char *)(x+i+3), (unsigned char *)(RK+31-i), (unsigned char *)(&u), 4);

        sm4_to_tao((unsigned char *)(&u), (unsigned char *)(&v), 4);

        w = L1(v);

        sm4_to_xor_2((unsigned char *)(x+i), (unsigned char *)(&w), (unsigned char *)(x+i+4), 4);

        x[i+4];
    }

    out[0] = x[35];
    out[1] = x[34];
    out[2] = x[33];
    out[3] = x[32];

    return 0;
}

int main()
{
    unsigned long mk[4] = {0x01234567, 0x89abcdef, 0xfedcba98, 0x76543210};
    unsigned long a[4] = {0x01234567, 0x89abcdef, 0xfedcba98, 0x76543210};
    unsigned long b[4] = {0};
    unsigned long c[4] = {0};

    sm4_one_enc(mk, a, b);

    sm4_one_dec(mk, b, c);

    printf("b[0]=[0x%08x], b[1]=[0x%08x], b[2]=[0x%08x], b[3]=[0x%08x]\n", b[0], b[1], b[2], b[3]);
    printf("c[0]=[0x%08x], c[1]=[0x%08x], c[2]=[0x%08x], c[3]=[0x%08x]\n", c[0], c[1], c[2], c[3]);

    return 0;
}

代码抄自 ： https://www.jianshu.com/p/58cc30625f16

参考:https://www.bilibili.com/video/BV1LS4y167r3?spm_id_from=333.999.0.0

__EOF__

本文作者：_TLSN
本文链接：https://www.cnblogs.com/lordtianqiyi/articles/16313062.html
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